Daniel dbawbaugh



(No Model.)

D. DRAWBAUGH.

TELEPHONE TRANSMITTER.

No; 297,578. Patented Apr. 29, 1884.

falls/y INVENTOR' I @W EWUE A H90 H4 ATTORNEYS N. PETERS. Phnblmwgnpher. Waning! D. c.

DANIEL DRAXVBAUGH, OF EBERLYS MILL, PENNSYLVANIA, ASSIGNOR TO THE PEOPLES TELEPHONE COMPANY, OF NEXV YORK.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 297,578, dated April 29, 1884.

Application filed November 12, 1883. (No model.) Patented in Belgium January 10, 1884, No. 63,802.

To all whom it may concern/.-

Be it known that I, DANIEL DRAWBAUGH, of Eberlys Mill, Cumberland county, Pennsylvania, have invented a new and useful Improvement in Telephone Transmitters, of

which the following is a specification.

The invention consists in a telephone-transmitter containing two coincidently-inclined electrodes not in electrical contact, the said IO electrodes being bridged by a third electrode, which rests upon them by gravity; also,in the particular construction herein set forth,whereby the electrodes, arranged as aforesaid, consist of a loose annular piece resting upon two I 5 fixed segmental pieces attached to the diaphragm; also,as a further and other improvement, in the construction and arrangement of said diaphragm and cover and means of supporting the same.

In the accompanying drawings, Figure 1 shows the instrument with the diaphragm and its cover removed. Fig. 2 is a vertical sectional view on the line :0 x of Fig. 1, the diaphragm and cover being in place. Fig. 3 is a rear view of the diaphragm with the electrodes in place. Fig. 4c shows theloose electrode,and Fig. 5 the fixed segmental electrodes and their supporting-plates.

Similar letters of reference indicate like 0 parts.

A, Fig. 1, is the back or base board of the instrument. B is a bar or ledge thereon, and O O are brackets.

Attached to the brackets G and bar B are cushions of felt or similar yielding material, D.

E is the diaphragm, here shown of wood or other non-conductin g material. Surrounding the diaphragm, on its outer or front, side, is a narrow spacing-piece, G. Outside of this piece G, and connected to it, is the cover H, preferably of wood, having a mouth-orifice, I. The spacing-rim G may be a mere bead or a raised rim integral with the diaphragm E or cover H, or with both. WVhen the diaphragm 5 is in place,the'upper part of its rear side bears against the pads or cushions D, and two screws, J, passing through said pads, secure the diaphragm to the bar B and bracket 0. The lower portion of the inner side of the diaphragm rests against one or more pieces of rubber tubing, K, which are slipped over pins L on the back board, A.

It will be apparent from the foregoing that the instrument has no inclosing case or box,- and that the diaphragm is supported and fixed only by the screws J.

The electrodes, which may consist of carbon, are supported upon the rear sideof the diaphragm. Said electrodes are three in numher, two of them being fixed upon said diaphragm and coincidently inclined, and so ar-' ranged as not to be in electrical contact with one another. The third electrode rests upon the two electrodes aforesaid by gravity, and forms a bridge between them. The shape of these electrodes is not material, nor is the manner of suspending the loose or bridge electrode to keep it in position. I consider the weight of the loose or bridge electrode to be of importance, inasmuch as I have obtained the best results with a loose electrode weighing about half an ounce. I also find that the apparatus works most satisfactorily when the fixed electrodes are so secured to the diaphragm as to stand at an inclination of about forty-five degrees.

The particular construction and mode of an ranging the electrodes shown in the drawings, which is the best means I now know of carrying the invention into practical effect, is as follows:

To the rear side of the diaphragm, and at about its center, is a bracket, M, of wood or other non-conducting material, having an inclined upper side. Upon said upper side are secured two metal socket-plates, O O. Said plates are not in contact with each other. Each plate receives one of the fixed electrodes P P, which are made in segmental form.

In the bracket M, and protruding through an opening between the carbons P P, is a hook-shaped post, Q, preferably of hard rubher or other non-conducting material.

B, Fig. 4., is the loose electrode,.which rests upon and thus forms a bridge between the fixed electrodes 1? P. This electrodeis here shown as an annular piece of carbon suspended or held in place by the arm Q, passing through its central aperture. V

It should be understood that I do not limit myself to two fixed electrodes of segmental form, nor to a loose electrode of annular form. Thus, for example, the fixed electrodes may be rectangular in shape, and the loose electrodes may be of like form. N or do I limit myself to a loose electrode having a central aperture to receive the arm Q, nor to a loose electrode necessarily supported by an arm or post passing through an aperture in it, inasmuch as said electrode may be suspended and maintained in place upon the fixed electrode by a thread or any flexible connection uniting it, for example, to the diaphragm. electrode is preferably made thicker at one edge than the other, so that it will tend to remain in position with its thickest or heaviest side lowest, and, if necessary, the board A may be slightly recessed to accommodate it.

The under side of said loose electrode is pref-.

erably provided with grooves, in order to ad-. mit air between the surfaces, as much as possible to avoid the effect of atmospheric pressure, which tends to press the electrodes uniformly together and to resist the movement of the loose electrode.

Tis the inductioncoil, inserted in a suitable socket in the base-board, and secured in place in any suitable manner-as, for example, by the metal bar U, attached to the bar 13.

The circuits in the instrument proceed as follows: from the battery to the binding-post 1, by the wire a, dotted lines, to post I), to the primary wire of the induction-coil T, to contact-piece c, Fig. 1; thence to contact-piece d, Fig. 3. These contact-piecc have holes through them, through which holes the screws J pass,

thus binding said pieces closely together..

Thence by wire 6 to the metal socket-plate O, to carbon 1?, to carbon R, to carbon 1?, to socket-plate O, to wire a, to contact-plate d, to contact-plate c, to post I) and wire a, and to the metal plate V.

WV is a bent metal plate secured by a rivet to the spring X. This spring normally presses the plate W in contact with the plate V, so that circuit continues from the plate V to the spring X, and thence by the wire f to the binding-post 2, and so back to the battery. The secondary circuit from the induction-coil T proceeds by the wires 9 5/ to the posts h h, and thence by wires 1 t" to the binding-posts 3 4, and thence to the line. Branch wires j j proceed from the posts h h to the bindingposts 5 6, to which a receiving-telephone may The loose duce a modification of the current passing through them, rendering said current undulatory, and capable of reproducing the speech or other sounds through the line and in the receiving-instrument.

Referring to the second improvement, it will also be observed that there is no box or inclosing-case, such as is commonly used in carbon transmitters, but that the interior of the instrument is open and exposed to view on three sides,- thus affording easy inspection of the same. The pads D and the rubber blocks or tubes K act not only as dampening-pads to stop out false vibrations not due to the voice, but also to prevent, in large measure, jars or vibrations of the partition or wall to which the instrument is attached being communicated to the diaphragm.

Y is an arm to receive the ring of the receiving-telephone, for suspending the latter when not in use. The ring, on passing upon the arm Y, raises the bar XV, which is thus moved out of contact with the plate V, breaking the local circuit in the instrument.

The diaphragm, when of wood, may be provided with a paper lining, F, to prevent splitting.

I claim as my invention-- 1. In a telephone, a diaphragm or soundreceiving surface, two fixed electrodes coincidently inclined or having their upper surfaces inclined in the same plane, the said electrodes not being in electrical contact with one another, a loose electrode superimposed upon both of said fixed electrodes and resting upon said electrodes by gravity, and a means of maintaining said loose electrode in position upon the fixed electrodes, substantially as described.

2. In atelephone, a vertical diaphragm, two fixed electrodes supported upon said diaphragm and not in electrical contact with one another, a loose electrode superimposed upon both of said fixed electrodes and resting upon them by gravity, and a means of'maintaining said loose electrode in position upon the fixed electrodes, substantially as described.

3. In a telephone, a diaphragm, a support secured to the rear side of said diaphragm and having an inclined upper surface, two fixed electrodes secured upon the inclined side of said support and not in electrical contact with one another, a loose electrode of like material resting upon said fixed electrodes, and a post of non-conducting material projecting from said support, and passing loosely through an aperture in said loose electrode, substantially as described.

4. In a telephone, a diaphragm rigidly fastened at one side and having a greater part of its periphery free and unattached, two electrodes inclined or having inclined upper surfaces supported uponsaid diaphragm, and not in electrical contact with one another, aloose electrode'of like material resting upon said fixed electrodes by gravity, and a means of supporting the loose electrode to prevent it near the free end thereof resting against a from sliding off the fixed electrodes, substantially as described.

5. In a telephone, a diaphragm, two fixed electrodes of semicircular segmental form, coincidently inclined, supported upon said diaphragm, and not in electrical contact with one another, aloose electrode, annular in form, and resting by gravity upon said fixed elec trodes, and a post projecting above said fixed electrodes, and passing loosely through the aperture in said loose electrode, substantially as described.

6. In a telephone, two electrodes, one of said electrodes being loose, of substantially wedge-shaped cross-section, or having one side made heavier than the other, so that when said electrode is suspended said weighted or thicker side may, by the action of gravity, assume a lower position than the unweighted or thinner side, the said loose electrode forming a bridge between the fixed electrodes, substantially as described.

7. In a telephone, the combination of the diaphragm E, support M, plates 0 O, fixed electrodes 1? I post Q, and loose electrode R, substantially as described.

8. I11 a telephone, a diaphragm rigidly secured at one end to a support, the greater part of the periphery of said diaphragm being unattached, a piece or pieces of elastic material being interposed between said diaphragm and the support, the inner side of said diaphragm piece or pieces of elastic material supported in contact with said side, but not attached thereto, substantially as described.

9. A telephone having no inclosing box or case, the electrodes being supported by the diaphragm, and the diaphragm being rigidly attached at one end to a support secured to the back or base board, substantially as described.

. 10. In a telephone, the combination of a diaphragm, E, supported at one end, the interposed frame or piece G, and cover H, having an orifice, I, the said cover being secured to and vibrating with the diaphragm, substan- G, cover H, bracket M, socket plates 0 O,

electrodes 1? P, electrode R, post Q, induction-coil T, and circuit-connections, substantially as described.

DANIEL DRAW BAUGH.

IVitnesses:

FRED. M. 0m, M. W. JACOBS. 

